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So, I'm currently on my mission to Duna with the Fremen Mk1, but I've come across a couple of problems that are really getting me down, so I'm calling it quits for the night.

First, my lander is seriously lacking in fuel. ∆v maps say 1380 for ascent to 52km. Is my lander with 1677∆v (KER calc) actually going to be able to make it into orbit seenextproblem ? I have not landed yet. Also, I have 1 drogue chute (the big red one) and two radials. Is this going to get me a safe landing without wasting my precious fuel? FYI: The lander is docked to the transfer tug right now, and I plan on leaving the tug in rendezvous orbit (50km) while I visit the surface.

When I set up my Duna encounter, I couldn't get the approach right and now I have a freaking RETROGRADE parking orbit. Now my transfer tug has loads of fuel, but is there an easy way to fix my orbit, or will I have to do a series of burns to get to a polar and then prograde orbit (destroying my 0.0005 (manual!) eccentricity and 178.7 inclination in the process)? I feel like this is going to be necessary as I seem to have little to no room for error on my ascent (if I can even land in the first place), but please correct me if I'm wrong - it would actually be a relief.

Help me Kerbalnauts! :( I've already had to waste months of mission time waiting for my ship to be not parallel to sunlight. (my solar panels literally said "Direct Sunlight" but "Energy Flow: 0.01")

Everybody saying retrograde orbits are ok are right, but if you still want to change it to a prograde orbit, the most efficient way to do it from a low orbit is not through a polar orbit.

Instead, you should make a prograde burn to make your orbit extremely elliptical. I mean it, the farther your apoapsis, the better. Set it just under the Duna SOI limit.
Then wait to reach your apoapsis. Here your velocity is minimal. Burn retrograde. Your velocity will drop to 0, then will rise again. Stop when your periapsis is back to where you want your low parking orbit to be. You're now in prograde orbit. Wait for the periapsis, and circularize.

This maneuver is vastly more efficient than changing your plane 180 degrees around the clock in low orbit.

You don't have to go all the way out to the edge of the SOI. You can probably do a flyby of Ike and let its gravity pull your trajectory around so that your Pe drops through the planet and rises out of the other side.

But if you aren't trying to dock with a craft going the other direction, don't worry about it. The higher delta v cost of landing from and launching into a retrograde orbit are less than the costs of reversing the orbital direction.

So just for clarification, your ship is currently in a retrograde orbit around Duna? You can land directly from a retrograde orbit. I'm not sure why you think you need to be in a prograde orbit, but you don't!! A prograde orbit may make landing precisely a little easier but it's not necessary.

In regards to landing/take off: With that much deltaV on t lander you should be able to get back Into orbit. The single drogue and 2 radials may be enough to land safely if timed correctly, but even if not it will lower your velocity significantly enough that you will only require a small amount of deltaV to land safely.

That's probably his thinking! The solution is just to do a retrograde gravity turn! I'm pretty sure the extra fuel requirement really isn't that much, really the only way to find out of the ship is capable is to try!

First, my lander is seriously lacking in fuel. ∆v maps say 1380 for ascent to 52km. Is my lander with 1677∆v (KER calc) actually going to be able to make it into orbit?

Prograde most likely, retrograde probably, it depends on where you land, your TTW and how good you are at getting to orbit (the gravity turn starts at 2km and is sharper than on kerbin). Even if you don't manage to get an orbit, should you get reasonbly high and somewhat fast, abandon ship and EVA into orbit, rescue your kerbals later with your interplanetary stage (well if you've got something to control it, but may be possible just to EVA there)

Also, I have 1 drogue chute (the big red one) and two radials. Is this going to get me a safe landing without wasting my precious fuel?

Depends on the mass of your lander, but unless it's very lightweight you're probably have to do a burn to slow down from like 20-50 m/s to reasonable landing velocity (it's not much fuel if you do it correctly). Also make sure you have very shallow descent profile so your parachutes don't tear off when they open.

When I set up my Duna encounter, I couldn't get the approach right and now I have a freaking RETROGRADE parking orbit.

Retrograde orbit doesn't change much lol. The only thing that changes is that you have to do spend like 60 m/s more when ascending to a retrograde orbit from duna. Duna rotates much slower than kerbin. When you do a interplanetary burn you just burn from the other side of the planet.
But if you really want to change your inclination for 180°, first change your orbit to a highly elliptical one (like even beyond Ike) and then change your inclination at Apoapsis. It takes less fuel than changing your inclination at 60km height but still takes a lot of delta v.

Also since you have alot of fuel in your interplanetary stage you may try landing with it :P

Thanks for the advice on Duna gravity turn, I couldn't find the optimal height anywhere.

Also since you have a lot of fuel in your interplanetary stage you may try landing with it :P

I did think of this, but I'm only using nukes. iirc (on my phone here), I only have like 1.66TWR (could be only 1.16) in vacuum (can't remember, but it's below 1.7). I'm not sure if i'll even have >1 on the surface.......However....I could just say fuck the lander and ditch it to shed mass, docking my can directly to the tug (this is what I was going to do after ascent and rendezvous, and it's a much more satisfying/correct itinerary). I was using KER for calcs, but I might just have to learn how to math and crunch some numbers. This mission's important!

Re 2, weird question, maybe I'm missing something but can't you just take off retrograde? Conflicting orbits are only a problem if you're trying to dock with something that's already there... you'll need a bit more speed, yes, to undo the rotational speed of the planet, but it doesn't sound like it should be THAT much.

[edit] Crazy idea, but maybe if it turns out you can't make orbit that way with the landing craft, you can try just getting it as high as possible, then catching up to it with the transfer tug? (WARNING: HARD)

I don't know what delta-v exactly is required to get to orbit from Duna but assuming that the delta-v map is right then yes, that should be plenty.

As for parachutes, it'll depend on how big your lander is. You can land on Duna with nothing but parachutes. If you think you're coming down a bit too fast then just fire your engines a bit just before touching down. This should only take a little bit of your delta-v. And really only just seconds before touching down, it's pointless to do it any earlier when you're coming down with parachutes.

It's tricky to plan your encounter from start so that you get to the right kind of orbit. What I usually do is I just set some encounter with as low a periapsis as I can and then fix it when I get in the sphere of influence of the target. It doesn't require much delta-v to change your trajectory when you're still at the edge of the SOI and you can use the manoeuvre nodes to get it right. Sure it would be more efficient to get it right at your ejection burn at Kerbin but it is difficult to do, the game just doesn't provide the tools to plan it easily.

If you're already in orbit, all is not lost. Turning your retrograde orbit into a prograde is going to take a lot of propellant, don't do that. Instead just land as normal and take off directly into a retrograde orbit. Instead of turning east (90 degrees in the navball) turn west (270 degrees). Duna's rotational surface velocity is only 30 m/s and you'll lose twice that for going into a retrograde orbit, so only 60 m/s in total. Seeing as you have quite a bit of excess delta-v in your lander, you should be able to do this easily.

Most of the ∆v maps I've seen don't include atmosphere; I usually allow about 2k to get up from Duna (and and have a smidge to spare. 1677 will be pushing it (depending on TWR).

For parachutes, it depends on weight and how much punishment your landing legs can take. There's a parachute calculator in the side-bar, but it doesn't take much dV for a last second landing burn.

Your retrograde problem is easy to solve. Decouple the lander and lower the periapsis for a retrograde entry (makes no difference for atmo landing) then raise your tug's apoapsis and burn normal (or retrograde) to change direction, then lower apoapsis again.

In future it's best not to circularize before decoupling your lander as the atmosphere will take care of that dV for you (and you then only have to use fuel for circularizing your tug -- I often wait until the lander is in orbit, then match its inclination as this is much easier than a precise ascent or carrying extra dV to meet your parking orbit).

Re. solar panel problems, you can use some RCS -- or failing that, get out and give the ship a nudge.

I suspect your only way to get the kerbals back up given the equipment they have will to finish circularizing their orbit(s) on pack fuel, then meet them with the tug (providing that it has sufficient room or perhaps ladders).

Aw piss, that's not too promising. My lander's pretty heavy. I don't remember what it weighs from the VAB. I'm not too worried about the lander legs, acceptable losses and all. But I don't think I'm going to make it into a rendezvous orbit. Great advice on the retro-pro thing, I might do that.

I also don't have any way to com back with my transfer stage alone. I brought no chairs and no chutes on that (Just used the RGS), and there is no RCS on the tug. All of my RCS is attached to the can, but I really need those 100 units for docking, as this will be my second time doing it. In the end, it looks like my craft was poorly designed. I should've gone to Dres instead, from the way my delta-v situation appears. stupidstupidstupid!

Well I'm gonna try anyway. I know I can land, but Bob might be there a while. Duna has not been kind to me yet; should have expected as much.

Just an update: everything worked out fine! I lowered my rendezvous orbit to 45km, and my landing was at the top of a canyon, ~5km altitude. I had like 15% fuel left too, after a powered descent (110 dV), ascent, and circularizing. Woohoo!

Chutes will help, definitely. How much - depends on your lander mass. Anyway, if it's not super heavy, you'll likely need to burn no more than 100 m/s a short time before touching down. Don't overdo it, chutes will cut if you go up.

Retrograde orbit is okay. To make it prograde, you'll need Δv of double your orbital velocity. But don't do that, just land and then go west (270) on ascent to get back into the retrograde orbit.